Method and apparatus for recording the temperatures of hot bodies



P. NEUBERT 2,085,508

METHOD AND APPARATUS FOR RE'CORDING THE TEMPERATURES OF HOT BODIES June 29, 1937.

Filed April 22, 1935 F. a n m fig. 2

Patented June V29, 1937 UNITED y i STATES PATENT OFFICE l 2,035,508 i Mli'rnon AND APPARATUS. non ancona-- me :ma

nomas TEMPERATURES F HOT raul Nennen, Leverkusen-1. G.,`werk, Germany;

assigner to I. G. Farbenindustrle Aktiengesellschaft, Franlrfort-on-tlie-Main,` Germany Application April sa, 1935, sei-isi N8. russ -In Germany Aprllv26f1934lg 'a claims. (ci. ca -'14) This invention relates to a method and apparatus for recording thetemperatures of single spots in temperature. ile ds. ,I The temperature of radiant hot bodies can be recorded by pyrometers recording the total rdiation and by pyrometers recording part 'of the radiation. 'I'he pyrometer's recording the total'radiation always require a large radiatingA area and in the case of technical instruments recording can be effected as low .as 400 C. LIn the case of pyrometersA recording only part of the radiation and also in the case of the modern color pyrometers, the temperatures of smaller areas, in certain cases-even of points. can be- '15 recorded. This, however, vcan only be eiectedi' vby means of the visible radiation sothat those instruments fail to ,Y The present invention is based on the dis- 0 rccvery that the principle of the process of Serial No. 654,952, led- Feb. 1, 1933, may also be advantageously applied to record temperatiu'es as.

low as 400 C. without visible radiation for proportionally smaller areas. U. S. Patent application Serial No. 654,952, tiled Feb. 1,- 193,3, de-

scribes-a `process in accordance with which such Y temperature iieldsare rendered visible by optil cally projecting the bodies on an excited luminous screen, the image-being produced by o the extinction of the luminescence of the screen caused by the infra-red rays radiated from the hot body. In accordance with the present invention it becomes possible to record the temperature directly on comparing the extinction 5 or blackening of the luminous screen with a standardized grey filter.

A'lhe accompanying drawingillustrates by' way of example in Figure 1 a' sectional viewvand in Figure 2 a cross section of a. device for carrying 40' out the process of the present invention. Referring to the drawing; in a casing I there is xed upon a hollow shaft 2 a white plane disc 3, for instance, a white cardboard or a white painted tin disc, upon which byv a lens 4 the body, the

temperature of `which is.to be recorded, is optically projected. The 'image appears on the disc in reflected light as it on a. ground glass screen and may be focused by means of a mirror l and an eye-piece I. vIn the optical axis .of the lens 4 there is on thedisc 3 a circle I8, of for instance 2 mm. diameter, which serves to focus the apparatus on thatV spot the temperature of which is to berecorded. The opposite part of the disc is covered with a layer of a luminescent substance'lwhichh'llinthecenteratthesame work at temperatures below,

distance from the axis as the circle on the-lower part of the disc a hole o! equal size behind which,

at a short distance, connected by an arm I9 with lfthe shaft 2 there is a smaller disc 8, which preferably is a little larger than the hole 20 in the disc 3. Initially by means of an incandescent lamp V9 through a, corresponding filter I0 the substance in the layer 1 and also the ,substance on the disc 8 are excited to luminescence until "the highest possible luminescence. is attained. Then the disc v8 is rotated by'means of the shaft 2 so that the part covered with the luminescent substance takes the 'place-of the free uncovered part. By this rotation a standardized grey filter II xed upon a glass plate 22 slides between the two luminescent plates I 'and 8. The grey illter II ends in-a screen 23 which, in its normal position lies behind the circle I8. To the shaft 2 there is further connected on the same side as the luminescent surface of the disc 3 a black filter I3 through which only infra red rays pene-A for a definite range of temperature, a screen I5,V

iirmly attached to a shaft I4 passing through the hollow shaft 2 is moved by means of a handie I8 to a position inv front of the lens and thereby the radiation is screened oir. During that time the hole 20 in the luminescent area 'I appears black, since the luminescent substanceV 8 is screened of! by means of the screen-23. On

turning back the grey iilterv II by means ofthe slide l1, until the tint of the un-extinguished luminescent substance 8 corresponds exactly tothe tint of the surroundings of the hole, that is to say the hole in the luminescent substance 'I disappears optically, the position `oi? the grey lter or its slide I'I which is, attached to the 'outside of the casing for moving the grey illter and which bears a mark, indicates a value lfor the extinction caused by the infra. red rays and thus a value for the strength t these rays, that is to Nsay for the temperature of the body optically Iscreened off at this spot.. Since the grey lter l and the mark havebeen standardized the temperature ofthe viewed spot of the hot body canv be read from the position of the slide I'I. On 65 Further, since the blackening of the excited` luminescent substance by the infra red rays increases with the passage of time it becomes possible by shortening the time of extinction also to record higher temperatures.

I claim:-

1. Method of measuring or indicating the temperature of spots on the surface of aV hot object having a temperature below the limit of visibility which comprises exciting a luminescent surface to luminescence, optically projecting an image of the object upon one portion of excited luminescent surface for a predetermined length of time by means of the infra-red rays emitted by said object while exc'sluding said radiation from a further portion of excited luminescent surface adjacent to said first portion, and measuring the difference in luminosity between the luminescent surface upon which the image has been projected and the luminescent surface from which the radiation has been excluded by extinguishing the difference in luminosity by means of a standardized gray wedge, whereby the position of the gray wedge is a measure of the difference in luminosity and therefore of the temperature of the corresponding spot on the object.

temperature of spots on the surface of a hot object having a temperature below the linut of visibility comprising a casing, at least one layer of luminescent substance arranged in the interior of the casing, a light source adapted to excite said substance intoluminescence when the substance is exposed thereto, means for interrupting the exposure of the luminescent substance to the light source, optical means for projecting an image of the object by means of infra-red rays radiated therefrom upon the luminescent substance, a

screen for excluding radiation from a portion of the luminescent substance during said projection, a gray wedge mounted for movement across the portion of luminescent substance covered by said screen, means for replacing said screen by said gray wedge, and* optical means for observing said gray wedge in juxtaposition to the luminescent substance vupon which the image has been projected.

3. -Apparatus for measuring or indicating the temperature of spots on the surface of a hot object Vhavir'ig a temperature below the limit of visibility comprising a casing, a screen rotatably positioned adjacent one wall of the casing, said screen having on one portion a surface of luminescent material with a hole in approximately the center thereof and upon a diametrically opposite portion a circle at the same distance from the axis of rotation of the screen as the hole. asecond screen positioned behind said hole and having a surface of luminescent material at least as large as the hole, a standardized gray filter wedge and a protective screen positioned between said first named screens and mounted for movement between the hole and the second screen, a light source adapted to excite the luminescent material, means for rotating the first named screen to expose the luminescent material separately to said light source and to infra-red radiation from the ob- 2. Apparatus for measuring or indicating the f ject, and optical means for observing the gray filter wedge through said hole in the first named screen. y

- PAUL NEUBERT. 

